Parametric Analysis of Doppler Coefficient of Reactivity in DUPIC Fuel by DRAGON

Abstract

Doppler coefficient of reactivity (DCR) is a crucial parameter in the evaluation of the reactivity-induced transients for both Light Water Reactor (LWR) and CANDU reactors. DCR of DUPIC (Direct Use of Spent PWR fuel in CANDU reactor) fuel, however, is less negative than natural uranium (NU) CANDU fuel in the - fresh condition and shifts toward a positive direction after irradiation. After benchmarking the DRAGON code with 89 group WIMS ENDF/B-V library on calculation of OCR in enriched U20 fuel and MOX fuel against MCNP-3A results, it was used to evaluate DCR in DUPIC fuel and to clarify the effects of changes in DUPIC fuel composition on DCR. A parametric analysis of DCR in DUPIC fuel shows that the presence of 0.3eV resonance cross section of PU239 plays an important role in shifting DCR toward a positive direction. The sign and magnitude of DCR are influenced by the PU239AJ235 ratio in the fuel.